Summary of Changes to

Keys to Soil Taxonomy

May, 2006

Chapter and page numbers refer to

Keys to Soil Taxonomy, ninth edition, 2003.

Chapter 3 – Horizons and Characteristics Diagnostic for the Higher Categories

  • Anthropic epipedon, P. 13 – Revised the definition so that it now stands on it’s own rather than referring to the mollic epipedon.
  • Plaggen epipedon , P. 15 – Definition expanded to include a list of required characteristics.
  • Mollic and Umbric epipedons, P. 14 & 15. Minor edits for clarification of criteria with no change in intended meaning.
  • Calcic and Gypsic horizons , P. 17 & 19 – Revised to more clearly describe the degree of cementation allowed.
  • Anhydrous Conditions – P. 22 - Definition expanded to include a list of required characteristics.
  • Andic Soil Properties, P. 22 - Revised and expanded the introductory paragraph. Edits made to required characteristics section for clarification (no change to meaning), and corrected error in syntax of equation.
  • Volcanic Glass, P. 26 – This is a new item added to the list of “Other Diagnostic Soil Characteristics” section (after “Spodic Materials”).
  • Ustic Moisture Regime, P. 33 – Corrected error in definition that prohibited it’s use with the cryic soil temperature regime.

Chapter 5 – Alfisols

  • Mollic & Umbric subgroups. – References to Ap horizons in the keys are changed to specify mixing to 18 cm.

Chapter 6 – Andisols

  • Duricryands – P 87, Add 2 new subgroups:
  • Eutric Oxyaquic
  • Oxyaquic

Chapter 8 – Entisols

  • Mollic & Umbric subgroups. – References to Ap horizons in the keys are changed to specify mixing to 15 cm.

Chapter 10 – Histosols

  • Cryosaprists, P. 162, add new subgroup:
  • Limnic

Chapter 11 – Inceptisols

  • Mollic & Umbric subgroups. – References to Ap horizons in the keys are changed to specify mixing to 15 cm.
  • Cryepts – P. 171, Major revisions to this great group.
  • Delete Eutrocryepts
  • Establish 3 new great groups
  • Humicryepts, with 15 subgroups
  • Calcicryepts, with 5 subgroups
  • Haplocryepts, with 17 subgroups
  • Revise the existing Dystrocryepts
  • Delete Humic, and Humic-Lithic subgroups.
  • Add 6 new subgroups
  • Sulfaquepts – P. 171, Corrected error in item number one for Hydraquentic subgroup to require 8 or more percent clay.
  • Durudepts – .P 174, Criteria revised to allow cemented layers in addition to Duripans.

Chapter 17 – Families and Series Differentiae and Names

  • Key to Particle-size Classes,P. 300:
  • Correct error in item B.2. that effectively prevented keying beyond the medial classes to the hydrous classes.
  • Strongly Contrasting Particle-size Classes, P. 301.
  • Add 3 new classes.
  • Ashy-skeletal over sandy or sandy-skeletal.
  • Medial-skeletal over sandy or sandy-skeletal.
  • Pumiceous or ashy pumiceous over loamy-skeletal.
  • Key to mineralogy classes, P. 303
  • Revise keying order to allow micaceous and paramicaceous to key out before parasesquic.
  • Several minor editorial revisions for clarification, with no change in meaning.

Chapter 18 – Designations for Horizons and Layers

Revisions to reflect changes to Horizon nomenclature resulting from ICOMANTH, P. 313.

  • New master horizon “M”, for manufactured layers.
  • New subscript “u”, for layers containing artifacts.
  • New prefix ^ for layers formed in human transported materials.

Appendix

  • Revised as needed to coordinate terms for laboratory procedures with the Laboratory Methods Manual, SSIR #42.
  • Added headings for “Physical Analyses”, “Chemical Analyses”, and “Mineral Analyses”.
  • Items under chemical analyses arranged alphabetically.
  • ODOE added under chemical analyses.
  • Mineral analyses discussion revised and expanded.

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